Among a large collection of alcohol material of Danish fleas, belonging to the Universitetets Zoologiske Museum at Copenhagen and kindly sent to me for identification by Dr S. L. Tuxen, was a tube which not only contained the fleas Chaetopsylla trichosa Kohaut (6 ♂, 22 ♀) and Paraceras melis melis (Walker) (3 ♂, 30 ♀), but also a large number of the chewing louse Trichodectes melis (Fabricius). These female of Trichodectes melis, is firmly attached on the outside of the left mid-tibia by having its mandibles entirely surrounding the tibia (Fig. 1). The two insects have been mounted on one slide (which is incorporated in the British Museum collection of fleas at Tring) and the attachment of the louse to the flea is so firm that the act of preparation did not separate the two insects.